(1) Field of the Invention
The present invention relates generally to an vehicle which runs autonomously on a route of travel toward a destination using a fuzzy control method.
(2) Background Art
Japanese Patent Application First Publication (JP-Al) Showa 62-162113 published on July 18, 1987 and Japanese Utility Model Registration Application First Publication (JP-Al) Heisei 1-15510 published on Oct. 25, 1989 exemplify a previously proposed autonomous vehicle running on a set route of travel.
A U.S. patent application Ser. No. 337,707 filed on Apr. 13, 1989 also exemplifies the previously proposed autonomous vehicle described above.
In Japanese Utility Model Application First Publication No. Heisei 1-15510, a camera which forms an image of the running route of the vehicle is installed on the vehicle to run the vehicle autonomously along a guide line, e.g., a white line on the route of travel.
In addition, in another previously proposed autonomous vehicle, a camera is used to observe left and right guide lines located in front of the vehicle at a constant distance and the steering wheel is driven so as to guide the vehicle between these guide lines.
Furthermore, the distance L at which the guidelines are observed is changed according to the vehicle speed V in the following way: EQU L=L.sub.o (1+.alpha..multidot.V)
L.sub.o, .alpha. denote constants.
However, although points to be visually observed can be changed according to vehicle speed in the previously proposed autonomous vehicle, only one visual point is scanned at one time, areas in front thereof being ignored. Therefore, the autonomous vehicle cannot remain in a centered position when running on a curved road or an S-shaped road. In addition, during operations such as driving on curved roads, the vehicle speed must be considerably reduced. Consequently, the running stability of the autonomous vehicle becomes reduced.